Bottom Brackets lasting weeks...

[BristolRich]

The other half has/is using her 18mth old Giant commuter style bike daily to get too and from work - 8 mile round trip. Up until starting to commute the bike had seen "light" use.

After completing 5-6 weeks of commuting she complained that the "crank was making a funny noise"... sure enough the sealed cartridge was on its way out showing signs of wear and play through the bearings within the bottom bracket cartridge.

This was replaced with a new Shimano BB cartridge and she was on her merry way for another 8 weeks or so problem free, until when riding home with her I noticed that the crank was creaking again. Sure enough the BB was worn again in similar fashion.

I've since replaced it with a cheapo job "for the time being" and noticed that this is now on its way out after another approx 5 or 6weeks.

The wear is definatly through the cartridge/bearings with the crank arm square tapers remaining clean and not showing signs of wear. The cartridges have been installed tightly into the frame with wear "feeling" like its formed on the front wheel side of the cartridge (as you'd expect?).

Have I been unlucky or anything else likely to be a cause?...Frame flex/ distortion?

Cheers

[Justin S]

Which BB are you fitting ? There are plenty of square taper ones, which are pretty rough nowadays. The best you can get within a sensible cost level would be the shimano UN55/ UN54's from Chain Reaction at just over a tenner, which is a bargain. Mate just bought a cheaper shimano one for his daughters bike and it was rougher than the one I took out !! UN55's have reasonable sealing, so should last a sensible lifespan.

[neilbauer]

My bike is in Halfords having the bottom bracket changed, it has been making noises since I bought it last year but now it's too noisey to ride. They fit cheap componants on low/mid range bikes to keep the pricing competative but fitting a cheap bottom bracket seems silly as it will fail and that's not good for the brand!

[jamiebae]

My singlespeed eats pedals, they last a few hundred KM and then go in the bin. I assume this is symptomatic of a bigger issue with the BB or cranks being out of alignment but pedals are cheap so I just keep replacing them!

[AyBee]

Does your OH put out massive power? I get through square taper BBs on my fixed commuter fairly regularly but by no means at the rate your OH is and since they're only £10 each, I treat them as a disposable item. Are you sure the BBs are knackered when you replace them? When mine creak, I take them out, clean them up, grease the threads and stick them back in and they go quiet and smooth again. I've got the whole process down to about 30 minutes

[Rolls]

jamiebae said:

My singlespeed eats pedals, they last a few hundred KM and then go in the bin. I assume this is symptomatic of a bigger issue with the BB or cranks being out of alignment but pedals are cheap so I just keep replacing them!

Every few hundred km
sod that for a laugh - that would be every couple of weeks for me!
that doesn't sound right at all!

[jamiebae]

Rolls said:

Every few hundred km
sod that for a laugh - that would be every couple of weeks for me!
that doesn't sound right at all!

The bike was €250 and it only gets used for local pottering around so it's not the end of the world. I assume the bike itself is fundamentally damaged in some way, but it does the job for now, or at least until I can justify an upgrade of my third bike...